Salinity dependence of complex conductivity of unconsolidated and consolidated materials: Comparisons with electrical double layer models

Weller, Andreas; Slater, Lee

doi:10.1190/geo2012-0030.1

Cited by 65 publications

(72 citation statements)

References 23 publications

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“…The low-frequency quadrature conductivity of clay-sand mixtures may be related to the clay content, but also to the different types of clays constituting the samples. It depends on their specific surface area and surface charge density or alternatively to their CEC (Leroy and Revil, 2009;Weller and Slater, 2012;Revil, 2013).…”

Section: Introductionmentioning

confidence: 99%

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

et al. 2014

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International audienceSpectral induced polarization or complex conductivity is a promising electric method in hydrogeophysics because of its sensitivity to water saturation, permeability, and particle size distribution (PSD). However, the physical and chemical mechanisms that generate the low-frequency complex conductivity of clays are still debated. To explain these mechanisms, the complex conductivity of kaolinite, smectite, and clay-sand mixtures was measured in the frequency range 1.4 mHz-12 kHz with various clay contents (100%, 20%, 5%, and 1% in volume of the clay-sand mixture) and salinities (distilled water, 0.1 g L-1, 1 g L-1, and 10 g L-1 of NaCl in solution). The results indicated the strong impact of the cation exchange capacity of smectite upon the complex conductivity of the material. The quadrature conductivity increased steadily with the clay content and was fairly independent of the pore fluid salinity. A mechanistic induced polarization model was also developed. It combined a Donnan equilibrium model of the surface electrochemical properties of clays and sand, a conduction model of the Stern and diffuse layers, a polarization model of the Stern layer, and a macroscopic conductivity model based on the differential effective medium theory. It also included the effect of the PSD. Our complex conductivity model predicted very well the experimental data, except for very low frequencies (<0.1 Hz) at which membrane polarization may dominate the observed respons

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Section: Introductionmentioning

confidence: 99%

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

et al. 2014

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“…Note that the dimensionless number R is also given by R/ B   . We also neglect below the salinity dependence of the surface and quadrature conductivities (Weller and Slater [2012], Weller et al [2013], Niu et al [2016]) but this dependence could be easily added to our model using the approach developed in Niu et al [2016]. The equivalent linear circuit of a soil can be sketched as in Figure 4 and can be seen as two resistances in parallel to a capacitance.…”

Section: A Modified Drake's Modelmentioning

confidence: 99%

Complex conductivity of soils

Revil

Coperey

Shao

et al. 2017

Water Resources Research

130

191

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The complex conductivity of soils remains poorly known despite the growing importance of this method in hydrogeophysics. In order to fill this gap of knowledge, we investigate the complex conductivity of 71 soils samples (including four peat samples) and one clean sand in the frequency range 0.1 Hz to 45 kHz. The soil samples are saturated with six different NaCl brines with conductivities (0.031, 0.53, 1.15, 5.7, 14.7, and 22 S m−1, NaCl, 25°C) in order to determine their intrinsic formation factor and surface conductivity. This data set is used to test the predictions of the dynamic Stern polarization model of porous media in terms of relationship between the quadrature conductivity and the surface conductivity. We also investigate the relationship between the normalized chargeability (the difference of in‐phase conductivity between two frequencies) and the quadrature conductivity at the geometric mean frequency. This data set confirms the relationships between the surface conductivity, the quadrature conductivity, and the normalized chargeability. The normalized chargeability depends linearly on the cation exchange capacity and specific surface area while the chargeability shows no dependence on these parameters. These new data and the dynamic Stern layer polarization model are observed to be mutually consistent. Traditionally, in hydrogeophysics, surface conductivity is neglected in the analysis of resistivity data. The relationships we have developed can be used in field conditions to avoid neglecting surface conductivity in the interpretation of DC resistivity tomograms. We also investigate the effects of temperature and saturation and, here again, the dynamic Stern layer predictions and the experimental observations are mutually consistent.

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“…Figure 6b shows the IP response (in-phase and quadrature conductivities) at 1.5 Hz of the core samples at different depths. As in Weller et al (2011) and Weller and Slater (2012), a direct relation between water conductivity and the real component of electrical conductivity was observed. In addition, the imaginary conductivity exhibits a steeper increase at low salinities and asymptotic behavior (flattens) at high water conductivity.…”

Section: Laboratory Measurements and Model Comparisonmentioning

confidence: 87%

Spectral induced polarization measurements for predicting the hydraulic conductivity in sandy aquifers

Attwa

Günther

2013

Hydrol. Earth Syst. Sci.

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Abstract. Field and laboratory spectral induced polarization (SIP) measurements are integrated to characterize the hydrogeological conditions at the Schillerslage test site in Germany. The phase images are capable of monitoring thin peat layers within the sandy aquifers. However, the field results show limitations of decreasing resolution with depth. In comparison with the field inversion results, the SIP laboratory measurements show a certain shift in SIP response due to different compaction and sorting of the samples. The SIP data are analyzed to derive an empirical relationship for predicting the hydraulic conductivity (K). In particular, two significant but weak correlations between individual real resistivities (ρ ) and relaxation times (τ ), based on a Debye decomposition (DD) model, with measured K are found for the upper groundwater aquifer. The maximum relaxation time (τ max ) and logarithmically weighted average relaxation time (τ lw ) show a better relation with K values than the median value τ 50 . A combined power law relation between individual ρ and τ with K is developed with an expression of A · (ρ ) B · (τ lw ) C , where A, B and C are determined using a least-squares fit between the measured and predicted K. The suggested approach with the calculated coefficients of the first aquifer is applied for the second. Results show good correlation with the measured K indicating that the derived relationship is superior to single phase angle models as Börner or Slater models.

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Salinity dependence of complex conductivity of unconsolidated and consolidated materials: Comparisons with electrical double layer models

Cited by 65 publications

References 23 publications

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

Spectral induced polarization of clay-sand mixtures: Experiments and modeling

Complex conductivity of soils

Spectral induced polarization measurements for predicting the hydraulic conductivity in sandy aquifers

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